Stepping motor controlling apparatus and method, and image reading apparatus and method

ABSTRACT

Stepping drive control of a motor is effected by synchronizing interruption to a CPU with N (in number) line triggers set to N times of one-line of an image. Further, in a synchronous mode in which phase control is effected in synchronous with N line triggers, acceleration/deceleration table can be switched not only by the N line triggers (external triggers) but also by internal triggers. With this arrangement, acceleration and deceleration of the motor is permitted within the N line triggers (external triggers) while being synchronized with the N line triggers (external triggers), thereby reducing a burden of software processing and realizing motor control corresponding to interruption of one line during high speed reading.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to apparatus and method forcontrolling a stepping motor, and an image reading apparatus, and moreparticularly, it relates to a technique regardingacceleration/deceleration and fixed speed control of a stepping motorused in an original conveyance controlling apparatus of a facsimile, anoriginal reading sensor shift controlling apparatus of a copying machineor a sheet feed controlling apparatus of a printer.

[0003] 2. Related Background Art

[0004] As a motor for controlling conveyance of an original in afacsimile or a motor of a reading portion in original reading sensorshift control in a copying machine, a stepping motor has conventionallybeen used. In control of the stepping motor, interruption output ortrigger output to a CPU and a stepping motor control unit wassynchronized with the interruption on the basis of one-line of an image,i.e., one step of the stepping motor, thereby effecting drive control ofthe motor.

[0005] Further, when an exciting current for the stepping motor wasdetermined by using PWM output, since the number of bits of the PWMoutput was fixed in dependence upon hardware, the motor driving suitablefor an image to be read could not be attained. Further, inacceleration/deceleration data tables for effecting phase control of thestepping motor, the number of the tables and the number of steps werefixed.

[0006] As mentioned above, in the original conveyance control in thefacsimile or the motor control of the reading portion in the originalreading sensor shift control in the copying machine, the drive controlwas effected by synchronizing the interruption output or trigger outputto the CPU and the stepping motor control unit with the interruption onthe basis of one-line of the image, i.e., one step of the steppingmotor. However, in such drive control, there arose a problem that aburden of software processing was increased. For example, as a readingspeed for the original was increased, an interval for interruptionprocessing to the CPU was shortened, and a ratio of interruption routineof software was increased or other software processing time wasincreased.

[0007] Further, since the number of bits of the PWM output fordetermining the exciting current of the motor was fixed, the number ofbits of the PWM output could not be changed. Thus, when a color image oran image having high resolving power was read at high speed in a highlyfine manner (instructed from an operating portion (not shown)), therearose a problem that a smooth current wave form could not be formed andsmooth motor driving could not be attained. Further, in theacceleration/deceleration data tables for effecting the phase control ofthe motor, since the number of the data tables was fixed, even if thenumber of data tables was not required, program data corresponding tothe number of data tables was required. Further, since the number ofsteps of the data table was fixed and a condition of a data table numbercould not read, if acceleration/deceleration control exceeding thenumber of acceleration/deceleration data tables was effected, renewalportions of a data table register and a present data table number had tobe grasped by software, which made software processing more complicated.

SUMMARY OF THE INVENTION

[0008] The present invention is made in consideration of theabove-mentioned conventional problems, and an object of the presentinvention is to reduce a burden of software processing of a CPU and toachieve motor control corresponding to one-line interruption during highspeed reading.

[0009] A second object of the present invention is to achieve high speedand highly fine reading having low burden of a CPU even when a memoryhaving small memory capacity is used.

[0010] A third object of the present invention is to obtain an optimumexciting current suitable for an image by changing the number of bits ofPWM output and to permit stable motor control even when a highly fineimage is read at a high speed.

[0011] A fourth object of the present invention is to permit selectionof optimum motor control by preparing a plurality of motor controlmodes.

[0012] A fifth object of the present invention is to permit of selectionof optimum motor control in accordance with attribution of an image.

[0013] A sixth object of the present invention is to provide apparatusand method for controlling a stepping motor, in which a burden ofsoftware processing of a CPU is reduced and a stable operation isrealized regarding reading stoppage due to poor memory, positionadjustment and acceleration/deceleration control in reading re-start,while driving a stepping motor at a high speed even with respect to acolor image having much image data amount and an image having fineresolving power.

[0014] To achieve the above objects, the present invention providesapparatus and method for controlling a stepping motor, comprisingsynchronous signal generating means for generating a synchronous signalhaving a period corresponding to N (natural number) times of one-line ofan image, line trigger producing means for producing N (in number) linetriggers in synchronous with generation of the synchronous signal, amotor control unit for controlling the stepping motor, and a CPU forcontrolling the motor control unit in synchronous with the generation ofthe synchronous signal, wherein the motor control unit effects motorcontrol until at least next synchronous signal is reached on the basisof the line triggers.

[0015] Further, the present invention provides the apparatus and methodfor controlling a stepping motor, in which the motor control unitincludes first memory means for holding timer data for advancing a phaseof the stepping motor and second memory means for holding the number ofsteps of the timer data, and the stepping motor is controlled on thebasis of the timer data and the number of steps.

[0016] Further, the present invention provides the apparatus and methodfor controlling a stepping motor, in which the motor control unit issynchronized with the line triggers produced by the producing means andcontrols acceleration/deceleration of the stepping motor by switchingacceleration/deceleration data tables comprised of the timer data andthe number of steps.

[0017] Further, the present invention provides apparatus and method forcontrolling a stepping motor, comprising synchronous signal generatingmeans for generating a synchronous signal for synchronizing with a motorcontrol unit, a motor control unit for controlling the stepping motor,and a CPU for controlling the motor control unit, and line triggerproducing means for producing N (in number) line triggers, wherein themotor control unit has a synchronous mode for controlling the steppingmotor in synchronous with generation of the synchronous signal and anon-synchronous mode for controlling the stepping motor regardless ofthe generation of the synchronous signal. When the synchronous mode isselected, the motor control synchronous with the synchronous signal iseffected, and, when the non-synchronous mode is set, the line triggerproducing means generates line triggers which are not synchronous withthe synchronous signal and the motor control unit controls the motor onthe basis of the line triggers which are not synchronous with thesynchronous signal.

[0018] Further, the present invention provides the apparatus and methodfor controlling a stepping motor, in which the synchronous signalgenerating means generates the synchronous signal having a periodcorresponding to N (natural number) times of one-line of an image, and,when the synchronous mode is selected, the line trigger producing meansproduces the line trigger synchronous with the synchronous signal, andthe motor control unit effects motor control until at least nextsynchronous signal is reached on the basis of the line triggersynchronous with the interruption (synchronous) signal.

[0019] Further, the present invention provides the apparatus and methodfor controlling a stepping motor, in which the motor control unitincludes first memory means for holding timer data for advancing a phaseof the stepping motor and second memory means for holding the number ofsteps of the timer data, and the stepping motor is controlled on thebasis of the timer data and the number of steps.

[0020] Further, the present invention provides the apparatus and methodfor controlling a stepping motor, in which the motor control unit issynchronized with the line triggers produced by the producing means andcontrols acceleration/deceleration of the stepping motor by switchingacceleration/deceleration data tables comprised of the timer data andthe number of steps.

[0021] Further, the present invention provides the apparatus and methodfor controlling a stepping motor, in which the synchronous mode isselected in case of an image having great memory usage amount and thenon-synchronous mode is selected in case of an image having small memoryusage amount.

[0022] Further, the present invention provides the apparatus and methodfor controlling a stepping motor, in which the synchronous mode isselected in case of a color image and the non-synchronous mode isselected in case of a monochromatic image.

[0023] Further, the present invention provides apparatus and method forreading an image, comprising reading means for reading an image withline unit, storing means for storing the read image, synchronous signalgenerating means for generating a synchronous signal having a periodcorresponding to N (natural number) times of one-line of the image, linetrigger producing means for producing N (in number) line triggers insynchronous with generation of the synchronous signal, a motor controlunit for effecting acceleration/deceleration control of the steppingmotor on the basis of the line triggers, a CPU for controlling the motorcontrol unit in synchronous with the generation of the synchronoussignal, judging means for judging a usage state of the storing means,and stop control means for causing the CPU to effect control forstopping the motor with respect to the motor control unit in synchronouswith the generation of the synchronous signal when the judge meansjudges that vacant capacity of the storing means is smaller than apredetermined value (or that usage amount of the storing means issmaller than a predetermined value), wherein the motor control uniteffects stop control for decelerating and stopping the motor on thebasis of the line triggers by means of the stop control means.

[0024] Further, the present invention provides the apparatus and methodfor reading an image, in which the judging means includes readingre-start instructing means for instructing re-start of reading when itis judged that the vacant capacity of the storing means is greater thanthe predetermined value.

[0025] Further, the present invention provides the apparatus and methodfor reading an image, in which, when the reading re-start instructingmeans instructs the re-start of reading in synchronous with thegeneration of the synchronous signal, the motor control unit acceleratesthe motor to reversely rotate the motor up to a position sufficient toeffect fixed speed driving to a deceleration starting position fromwhich deceleration is started by the stop instruction, therebypermitting the re-start of reading at a high speed again.

[0026] Further, the present invention provides the apparatus and methodfor reading an image, wherein the motor control unit has a synchronousmode for controlling the stepping motor in synchronous with thegeneration of the synchronous signal and a non-synchronous mode forcontrolling the stepping motor regardless of the generation of thesynchronous signal, and when the non-synchronous mode is selected, theline trigger producing means generates the N (in number) line triggersregardless of the generation of the synchronous signal and the motorcontrol unit controls the motor on the basis of the N line triggerswhich are not synchronous with the synchronous signal.

[0027] Further, the present invention provides the apparatus and methodfor reading an image, in which the synchronous mode is selected in caseof an image having great memory usage amount and the non-synchronousmode is selected in case of an image having small memory usage amount.

[0028] Further, the present invention provides the apparatus and methodfor reading an image, in which the synchronous mode is selected in caseof a color image and the non-synchronous mode is selected in case of amonochromatic image.

[0029] Further, the present invention provides apparatus and method forcontrolling a stepping motor, comprising synchronous signal generatingmeans for generating a synchronous signal having a period correspondingto N (natural number) times of one-line of an image, line triggerproducing means for producing N (in number) line triggers in synchronouswith generation of the synchronous signal, a motor control unit forcontrolling the stepping motor, and instruction receiving means forreceiving a motor control instruction from a CPU in synchronous with thegeneration of the synchronous signal, wherein the motor control uniteffects motor control until at least next synchronous signal is reachedon the basis of the line triggers.

[0030] Further, the present invention provides the apparatus and methodfor controlling a stepping motor, in which the motor control unitincludes first memory means for holding timer data for advancing a phaseof the stepping motor and second memory means for holding the number ofsteps of the timer data, and the stepping motor is controlled on thebasis of the timer data and the number of steps.

[0031] Further, the present invention provides the apparatus and methodfor controlling a stepping motor, in which the motor control unit issynchronized with the line triggers produced by the producing means andcontrols acceleration/deceleration of the stepping motor by switchingacceleration/deceleration data tables comprised of the timer data andthe number of steps.

[0032] Further, the present invention provides apparatus and method forcontrolling a stepping motor, comprising synchronous signal receivingmeans for receiving a synchronous signal for synchronizing with a motorcontrol unit, a motor control unit for controlling the stepping motor,instruction receiving means for receiving motor control instruction froma CPU, and line trigger producing means for producing line triggers at aperiod corresponding to one line of an image, wherein the motor controlunit has a synchronous mode for controlling the stepping motor insynchronous with receipt of the synchronous signal and a non-synchronousmode for controlling the stepping motor regardless of receipt of theinterruption (synchronous) signal. When the synchronous mode isselected, the instruction receiving means receives the motor controlinstruction from the CPU in synchronous with generation of thesynchronous signal and the motor control unit effects motor control onthe basis of the instruction received by the instruction receivingmeans, and when the non-synchronous mode is set, the line triggerproducing means produces the line triggers which are not synchronouswith the synchronous signal and the motor control unit effects the motorcontrol on the basis of the line triggers which are not synchronous withthe synchronous signal.

[0033] Further, the present invention provides the apparatus and methodfor controlling a stepping motor, wherein the synchronous signalreceiving means receives the synchronous signal having a periodcorresponding to N (natural number) times of one-line of the image, andwherein, when the synchronous mode is selected, the line triggerproducing means produces a line trigger which is synchronous with thesynchronous signal and the motor control unit effects the motor controluntil at least next synchronous signal is reached on the basis of theline trigger which is synchronous with the synchronous (interruption)signal.

[0034] Further, the present invention provides the apparatus and methodfor controlling a stepping motor, in which the motor control unitincludes first memory means for holding timer data for advancing a phaseof the stepping motor and second memory means for holding the number ofsteps of the timer data, and the stepping motor is controlled on thebasis of the timer data and the number of steps.

[0035] Further, the present invention provides the apparatus and methodfor controlling a stepping motor, in which the motor control unit issynchronized with the line triggers produced by the producing means andcontrols acceleration/deceleration of the stepping motor by switchingacceleration/deceleration data tables comprised of the timer data andthe number of steps.

[0036] Further, the present invention provides the apparatus and methodfor controlling a stepping motor, in which the synchronous mode isselected in case of an image having great memory usage amount and thenon-synchronous mode is selected in case of an image having small memoryusage amount.

[0037] Further, the present invention provides the apparatus and methodfor controlling a stepping motor, in which the synchronous mode isselected in case of a color image and the non-synchronous mode isselected in case of a monochromatic image.

[0038] Further, the present invention provides the apparatus and methodfor controlling a stepping motor, in which the motor control unitincludes PWM output data storing means for holding PWM output datahaving a predetermined the number of bits for determining an excitingcurrent for the stepping motor, and PWM output means for outputting thePWM data stored in the PWM output data storing means in synchronous witha phase of the stepping motor, and wherein the stepping motor iscontrolled by setting the number of bits of the PWM data outputted fromthe PWM output means.

[0039] Further, the present invention provides the apparatus and methodfor reading an image, wherein the motor control unit includes PWM outputdata storing means for holding PWM output data having a predeterminedthe number of bits for determining exciting current for the steppingmotor, and PWM output means for outputting the PWM data stored in thePWM output data storing means in synchronous with a phase of thestepping motor, and wherein the stepping motor is controlled by settingthe number of bits of the PWM data outputted from the PWM output means.

[0040] Further, the present invention provides the apparatus and methodfor controlling a stepping motor, in which the motor control unitincludes step-up or step-down number storing means for holding a step-upnumber or a step-down number of the acceleration/deceleration table, andstep-up or stepdown of the acceleration/deceleration table is effectedon the basis of the step-up number or the step-down number held by thestep-up or step-down number storing means.

[0041] Further, the present invention provides the apparatus and methodfor controlling a stepping motor, in which the motor control unitincludes table number storing means for holding a table number of theacceleration/deceleration tables, step-up or step-down of theacceleration/deceleration table is stopped on the basis of the tablenumber held by the table number storing means.

BRIEF DESCRIPTION OF THE DRAWINGS

[0042]FIGS. 1A and 1B, combined as shown in FIG. 1, are block diagramsshowing a construction of a stepping motor controlling apparatusaccording to an embodiment of the present invention;

[0043]FIG. 2 is a timing chart showing an example of the stepping motorcontrolling apparatus according to the embodiment of the presentinvention;

[0044]FIG. 3 is a timing chart showing an example of the stepping motorcontrolling apparatus according to the embodiment of the presentinvention in a reading stop condition;

[0045]FIG. 4 is a timing chart showing an example of position adjustmentin reading re-start in the stepping motor controlling apparatusaccording to the embodiment of the present invention;

[0046]FIG. 5 is a timing chart showing an example of the stepping motorcontrolling apparatus according to the embodiment of the presentinvention in a reading re-accelerating condition;

[0047]FIG. 6 is a flow chart showing an example of processing sequenceof an acceleration/deceleration table associated with phase shift of thestepping motor controlling apparatus according to the embodiment of thepresent invention;

[0048]FIG. 7 is a flow chart showing an example of control sequence ofPWM output of the stepping motor controlling apparatus according to theembodiment of the present invention; and

[0049]FIG. 8 is a view showing an example of register setting of anacceleration/deceleration table comprised of timer data and a steppingmotor of the stepping motor controlling apparatus according to theembodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0050] The present invention will now be fully explained in connectionwith embodiments thereof with reference to the accompanying drawings.

[0051]FIGS. 1A and 1B, combined as shown in FIG. 1, are block diagramsshowing an example of a construction of a stepping motor controllingapparatus according to an embodiment of the present invention. In FIGS.1A and 1B, the stepping motor controlling apparatus includes a CPU 1 forcontrolling the entire apparatus (including reading control), an imageprocessing block 2 for effecting various processing operations such asresolving power (or resolution) conversion and magnification change ofan image, a motor control unit 3 for effecting data setting and controlfor motor driving, a ROM 31 for storing a program for effecting a basicoperation of motor control, a reader unit 33 for inputting the image asdata through a CCD (charge coupled device) or a CS (contact sensor), aRAM 32 for storing image data read by the reader unit 33, and a divider30 for producing a divided clock of a system clock. The reader unit 33are so arranged as to read a color image and a monochromatic image in aconventional manner. Further, on the basis of an instruction from anoperating portion (not shown), color reading or monochromatic readingcan be instructed as a reading method. Further, regarding a resolvingpower for reading image, a plurality of resolving powers can beinstructed. As mentioned above, the stepping motor controlling apparatusaccording to the present invention forms a part of an image readingapparatus.

[0052] The motor control unit 3 is constituted by four blocks. A firstblock is a block for controlling an exciting phase and an excitingcurrent, which block is constituted by a 14-bit exciting (ormagnetizing) pattern register 4 for storing an exciting pattern and PWMdata (4:0) (here, (4:0) represents a 5-bit signal) of A-phase andB-phase, an exciting data selector 5 for selecting the exciting patternby phase number data PH (3:0) (here, (3:0) represents a 4-bit signal) ofan exciting phase counter 10 for counting the exciting phase, and anexciting phase number register 9 for storing the phase number data PH(3:0).

[0053] A second block is a block for effecting PWM (pulse widthmodulation) output for controlling phase output and exciting current,which block is constituted by an exciting phase output portion 6 foroutputting an exciting phase pattern D (3:0) selected by the excitingdata selector 5, a current power-down PWM register 11 (3:0) which is setwhen power-down of the exciting current is effected, a PWM selector 7for selecting an exciting current pattern (13:4) selected by theexciting data selector 5 and a current power-down PWM value, a PWMoutput portion 8 for outputting the selected PWM value, a currentpower-down timer register 13 for storing time data until the current ispowered-down, a PWM counter 12 for counting a current power-down timerand for outputting a selection signal to the PWM selector 7, a currentpower-down XSH trigger register 15 for storing XSH (line trigger) numberuntil the current is powered-down, and an XSH counter 14 for countingcurrent power-down XSH trigger number and for outputting a selectionsignal to the PWM selector 7.

[0054] A third block is a block for effecting phase shift on the basisof timer data for advancing the phase and step data, which block isconstituted by an exciting timer table 24 for storing exciting timerdata, a step data table 25 for storing data (step data) regarding thenumber of steps of the timer, a data selection counter 22 for counting atable number of an acceleration/deceleration data table comprised of thetimer data and the step data and for outputting a selection signal, anexciting timer selector 20 for selecting the exciting timer datacorresponding to the table number on the basis of the selection signaloutputted by the data selection counter 22, a step count selector 21 forselecting the step data corresponding to the table number selected onthe basis of the selection signal, an exciting timer 16 for counting theexciting timer data selected by the exciting timer selector 20, a stepcounter 17 for counting the step data selected by the step countselector 21, a data table maximum number setting register 19 for storinga maximum table number of the acceleration/deceleration data table, anup-down count selecting portion 18 for outputting a control signal foreffecting count-up or count-down of the acceleration/deceleration datatable, and an acceleration/deceleration data table step number register23 for storing the number of steps in the step-up or the step-down ofthe acceleration/deceleration data table.

[0055] An XSHDIV signal is an interruption output from the imageprocessing block 2 to the CPU and is an N-line trigger set to N times ofone-line of an image. Here, while an example that N is set to 16 will beexplained, the present invention is not limited to such an example, Nmay be set to 32 or 8. Further, when N=1, the N-line trigger to the CPUis generated with one line unit. This case is suitable when the image isread with highly fineness at a low speed. A fourth block is a block forproducing an internal trigger XSH interval from the N-line trigger(XSHDIV signal), which block is constituted by an XSH interval (referredto as “XSHINT” hereinafter) delay setting register 26 for storing adelay time of the internal trigger, an XSHINT delay counter 27 forcounting an XSHINT delay value, and an SXH trigger generator 28 forproducing the internal trigger having a period equal to or shorter thanthe N-line trigger. The internal trigger (XSHINT) has a period same asthat of one-line of the image, i.e., one-line image data outputted fromthe reading unit 33.

[0056] A read register 29 of the motor control unit 3 serves to outputmotor setting condition output (STS) representing a setting condition ofthe motor control unit by address setting, phase number data (PH)representing a phase condition of the motor, data table number data(DTN) representing the acceleration/deceleration data table number, andexciting pattern condition output (MD) representing a current excitingpattern condition, as read data.

[0057]FIG. 2 is a view showing an embodiment of a timing chartrepresenting a synchronous mode of the stepping motor controllingapparatus shown in FIGS. 1A and 1B.

[0058] The XSHDIV signal is an interruption output from the imageprocessing block 2 to the CPU and represents an N-line trigger set to Ntimes of one-line of the image. Here, since the N-line triggers effectsonly one interruption to the CPU during the reading of 16-line image.The CPU can perform other processing operation efficiently.

[0059] On the basis of the XSHDIV signal, the CPU 1 outputs drivecommand, stop command or motor reverse command to the motor controlunit.

[0060] The internal trigger (XSHINT signal) is produced to besynchronized with the interruption signal inputted to the motor controlunit 3. In the timing chart according to the illustrated embodiment, theperiod of the N-line trigger is set to 16 times of the internal trigger(XSHINT signal). Further, internal trigger delay shown in FIG. 2 is setto 0 (zero; none).

[0061] Here, while an example that the period of the N-line trigger(XSHDIV) is set to 16 times of the period of the internal trigger(XSHINT) will be explained, the present invention is not limited to suchan example, but the former may be set to 32 times or 8 times of thelatter. Further, when N=1, the N-line trigger to the CPU is generatedwith one line unit. This case is suitable when the image is read withhighly fineness at a low speed. An XENRTP signal is an enable signal foran internal circuit of the motor control unit 3 and becomes active whenXENRTP is Low. An SYN signal is a signal for settingsynchronism/non-synchronism with the N-line trigger (XSHDIV signal),and, when the SYN signal is High, a synchronous mode is selected. Whenthe SYN signal is Low, a non-synchronous mode is selected.

[0062] The synchronous mode is a mode in which timings of the imageprocessing block 2 and the motor driving are synchronized and the motorcontrol unit 3 can be controlled by the CPU 1. In this mode, the motorcontrol unit 3 effects the motor control until at least next N-linetrigger is reached without giving a burden to the CPU 1. Further, sincea position of the image being actually read and a motor driving amountare adjusted in the synchronous mode, the synchronous mode is suitablefor a stopping operation on the reading during the reading and are-starting operation of the reading. Accordingly, the synchronous modeis suitable when the image having great memory usage amount such as acolor image or an image having high resolving power is read. Since thestop of the reading during the reading and the reading re-start can beeffected, the image having high resolving power can be read at a highspeed by using a memory having small memory capacity.

[0063] Here, the CPU 1 is set so that, when the reading of the colorimage or the image having high resolving power is designated via theoperating portion (not shown), the synchronous mode is selected.

[0064] On the other hand, the non-synchronous mode is a mode in whichthe internal trigger is produced when the XENRTP signal outputted fromthe CPU 1 and other operation conditions are satisfied, and the motorcontrol is effected up to end of one page regardless of the N-linetrigger by driving motor.

[0065] Namely, in the non-synchronous mode, the motor control unit 3 canperform the start of the motor driving and timing adjustment withrespect to the image processing block 2 on the basis of the XENRTPsignal, a HOLD signal (described later), etc. and perform the motorcontrol without acting the load on the CPU 1 until the reading of theimage in one-page is finished. Thus, the non-synchronous mode issuitable when the image having small memory usage amount such as amonochromatic made which does not require the stop of the motor duringthe reading and the re-start.

[0066] The HOLD signal is a signal which is outputted from the CPU 1 andgives the exciting current to the motor without effecting the phaseshift and holds the motor to a hold condition. When the HOLD signal isHigh, a hold mode is attained. On the other hand, when the HOLD signalbecomes Low, the motor is changed to a drive permitting condition. Inthe non-synchronous mode, when the HOLD signal becomes Low, the motordriving is started.

[0067] A TIMD Load represents a timing for loading timer data (T1 inTIMDATA) to the exciting timer 16 via the exciting timer table 24. AnSTPD Load represents a timing for loading step data (STPDATA; forexample, 07H) to the step counter 17 via the step data table 25. Whenthe counting is effected up to data T1 by a timer counter in theexciting timer 16, TIMCARRY (carry of timer counter) is outputted. Whenthe TIMCARRY is outputted, the step data is counted by the step counter17. In the example shown in FIG. 2, the down-count is shown, butup-count also is effected in the similar manner.

[0068] When the step data becomes 00H (in down-count) or for example setdata 07H (in up-count), the exciting timer 16 outputs STPCARRY (carry ofstep counter). When the STPCRRY is outputted, the step counter 17advances the count of the acceleration/deceleration data table comprisedof the timer data and the step data in accordance with the set tablestep number. If the STPCARRY (step carry) is not outputted, after theTIMCARRY (timer carry) is outputted, the timer data is loaded to theexciting timer 16 again, and the count is started.

[0069] A DATSIF signal which is a signal for advancing phase data(PHASE) is outputted when the TIMCARRY is outputted, thereby chargingthe excitating current and the phase. In the illustrated timing chart,an embodiment of exciting currents IA, IB of W1-2-phase excitation(micro step driving) is shown.

[0070] A TABLENUM (table number) of an acceleration/deceleration datatable comprised of the exciting timer data and the step data iscounted-up (or counted-down) by the data selection counter 22 on thebasis of the STPCARRY (step carry) signal. By this operation, theswitching of the acceleration/deceleration data table is effected.

[0071] As mentioned above, by using the non-synchronous mode, since themotor driving amount is not synchronous with the reading position of theimage, when the image for one-page is read without stopping, the burdenof the CPU can be reduced greatly. However, if the image for one-pagecannot be stored in the memory and thus the motor is stopped on the way,the reading position is not aligned with the stop position of the motor.In this case, since the image must be read again at the beginning, it isvery inconvenient. In such a case, by using the synchronous mode, thestop of reading of the image and the re-start can easily be performedwithout reading the image at the beginning. Further, since the stop ofreading of the image and the re-start can be effected on the way of thereading, the capacity of the image memory can be reduced.

[0072] Now, the processing regarding the reading stop and readingre-start using the synchronous mode will be explained.

[0073] Here, in the non-synchronous mode, since the other signals arethe same as those shown in FIG. 2 except that the non-synchronous modeis operated regardless of the N-line trigger (XSHDIV signal),explanation thereof will be omitted.

[0074]FIG. 3 is a view showing an embodiment of a timing chart regardingthe reading stop of the stepping motor controlling apparatus shown inFIGS. 1A and 1B. In the timing chart according to the illustratedembodiment, an example that the period of the N-line trigger (XSHDIVsignal) is set to 16 times of the period of the internal trigger (XSHINTsignal) is shown.

[0075] First of all, when the CPU 1 judges that the vacant capacity ofthe RAM 32 as the memory for storing the image data is below apredetermined capacity in accordance with the program stored in the ROM31, the CPU 1 outputs STOP command for stopping the motor to thestepping motor control unit 3 between the N-line trigger (XSHDIVsignal). Then, in synchronous with the N-line trigger (XSHDIV signal),the deceleration control of the motor is performed in accordance withthe deceleration table previously written in the motor control unit,thereby stopping the motor. If the CPU 1 judges that the vacant capacityis reserved in the memory, although the reading is re-started, regardingimage line data within the deceleration range, the following processingcan be considered. If the reading is re-started after the motor isre-accelerated by reverse switch-back, the image data in thedeceleration range is abandoned. Alternatively, if the reading isre-started at a low speed requiring no acceleration or if the reading inre-acceleration is performed, the image data is reserved. Here, while anexample that the motor is stopped within the period (16 lines) of theN-line triggers (XSHDIV signal) was shown, the same is true so long asthe memory corresponding to the deceleration lines can be maintainedeven if the period of the XSHDIV signal is exceeded.

[0076] Here, while an example that the deceleration/stop of the motor iseffected when the vacant capacity of the memory is reduced below thepredetermined capacity was explained, a case where the deceleration/stopof the motor is effected when the vacant capacity of the memory isincreased above a predetermined capacity is also included within thescope of the present invention.

[0077]FIG. 5 is a view showing an embodiment of a timing chart regardingpositional adjustment in the reading re-start in the stepping motorcontrolling apparatus shown in FIG. 1.

[0078] The CPU 1 outputs reverse command (ROLIMOD=1) for rotating themotor reversely to the stepping motor control unit 3 between the N-linetriggers (XSHDIV signal). Then, in synchronous with the N-line trigger(XSHDIV signal), the reverse control is performed in accordance with thereverse table previously written in the motor control unit. As a result,the motor performs reverse switch-back by an amount corresponding to thephase data required for acceleration/deceleration to coincide with thephase data upon initiation of deceleration.

[0079]FIG. 5 is a view showing an embodiment of a timing chart in thereading re-acceleration in the stepping motor controlling apparatusshown in FIG. 1.

[0080] The CPU 1 outputs START comman for starting the motor to thestepping motor control unit 3 between the N-line triggers (XSHDIVsignal). Then, in synchronous with the N-line trigger (XSHDIV signal),the motor control unit 3 performs the re-acceleration control inaccordance with the acceleration previously written in the motor controlunit. In this case, the motor control unit 3 controls the motor so thatthe reading can be re-started up to the deceleration starting position.

[0081] In this way, the image can be read without distortion whilesynchronizing with the reading timing of N lines even when the stopcontrol, reverse switch-back control and/or re-acceleration control isperformed on the way of the reading. Further, even in case of high speedreading, since the frequent interruption (such as interruption for eachline unit) is not executed, the burden of the CPU 1 can be reducedconsiderably.

[0082] Here, while an example that the motor is stopped by outputtingthe STOP command when the vacant capacity of the memory is reduced belowthe predetermined value was explained, the present invention is notlimited to such an example, but, for example, the following method maybe used.

[0083] That is to say, the motor driving command is outputted to themotor control unit in synchronous with the N-line trigger (XSHDIVsignal) until the vacant capacity of the memory is reduced below thepredetermined value, and, if the vacant capacity of the memory isreduced below the predetermined value, the motor driving command is notoutputted in synchronous with the N-line trigger (XSHDIV signal). Bydoing so, the effect similar to that obtained when the STP command isoutputted can be achieved, and, thus, such a method is also included inthe scope of the present invention.

[0084] Next, control sequence of the acceleration/deceleration datatable regarding the phase shift in the stepping motor controllingapparatus according to the illustrated embodiment will be explained withreference to a flow chart shown in FIG. 6.

[0085] First of all, initial setting of the motor control unit iseffected (step S3001). The initial setting includes triggersynchronous/non-synchronous mode setting, rotational direction setting,acceleration/deceleration data table step-up/step-down setting, outputmode setting, motor control unit enable setting and the like. Then, thestep data is loaded to the stepping counter 17 (step S3002). Then, it isjudged whether the initially set mode is the synchronous mode (colormode)(SYN=1) (step S3003). If it is the synchronous mode (color mode),whether the N-line trigger (XSHDIV signal) is inputted or not (stepS3004) is judged. If XSHDIV=0, synchronism with the XSHINT signal as theinternal trigger (step S3005) is effected. In the step S3004, ifXSHDIV≠0, the sequence goes to a step S3006. Then, it is judged whetherthe internal trigger is inputted (XSHINT=L) or not (step S3006). Ifinputted, the DATSIF as the phase shift signal is changed to High,thereby loading the exciting timer data (step S3007). Incidentally, inthe step S3003, if the initially set mode is the non-synchronous mode(SYN=0) or monochromatic mode, the sequence goes to the step S3007. Inthe step S3006, if the internal trigger is not inputted, i.e., ifXSHINT=H, an internal trigger waiting condition is continued.

[0086] Then, in the step S3005, the timer data is loaded and thecount-up or the count-down of the exciting timer is carried out (stepS3008). If the timer data setting value is reached, the timer carry isoutputted (TIMCARRY=H)(step S3009).

[0087] Then, the count-up (in case of up counter) or the count-down (incase of down counter) of the step data is performed (step S3010). Whenthe value of the step counter 17 becomes the sep data setting value (incase of up counter) or 00H (in case of down counter), it is judgedwhether the step carry is outputted (STPCARRY=H) or not (step S3011). Ifthe step carry is outputted, it is judged whether the setting of up/downmode of the acceleration/deceleration data table is an up-count mode(UDMOD=0) or not (step S3012). If the up-count mode, theacceleration/deceleration data table is counted-up (step S3013). Then,it is judged whether the acceleration/deceleration data table counter isgreater than the set data table number (DataTableCOUNT>MAXNUM) or not(step S3015). If greater than the set acceleration/deceleration datatable number, the set table number (MAXNUM) is inputted to theacceleration/deceleration data table number SD (3:0) (step S3017). Inthe step S3015, if the acceleration/deceleration data table counter issmaller than the set data table number, the counted-up count value (NUM)is inputted to the acceleration/deceleration data table number SD (3:0)(step S3018).

[0088] In the step judgement (step S3012), if the setting of up/down ofthe acceleration/deceleration data table is a down count mode (UDMOD=1),the acceleration/deceleration data table is counted-down (step S3014).Then, it is judged whether the acceleration/deceleration data tablecounter is smaller than 1 (DataTableCount<1) or not (step S3016). Ifsmaller than 1, data 01H is inputted to the acceleration/decelerationdata table number SD (3:0) (step S3019). In the step S3016, theacceleration/deceleration data table counter is not smaller than 1, thecounted-down count value (NUM) is inputted to theacceleration/deceleration data table number SD (3:0) (step S3020).

[0089] Here, the reason why the judgement reference is set to 1 (orless) in the step S3016, is that, when the number of steps of theacceleration/deceleration data table is set to 2 steps for example, thecount value may become 0 (zero). In the steps S3017 to S3020, after theacceleration/deceleration data table number SD was set, the sequence isreturned to the step S3002, and the above-mentioned operations arerepeated.

[0090] As shown in FIG. 6, the acceleration/deceleration data tablenumber is fixed to the ultimately set acceleration/deceleration datatable number or 01H. This means that, after the acceleration ordeceleration of the motor is completed, fixed speed rotation iscontinued. In the example shown in FIG. 6, in order to stop the motor,for example, the exciting current may be stopped by an enable signal ofthe motor control unit, for example.

[0091] Next, control sequence of PWM output of the stepping motorcontrolling apparatus according to the illustrated embodiment will beexplained with reference to a flow chart shown in FIG. 7.

[0092] First of all, when the start of reading of the image isinstructed, initial setting of the motor control unit 3 is effected(step 4001). The initial setting regarding the PWM output portion 8includes setting of PWM data (5 bits) for generating desired excitingcurrent included in the exciting pattern data, setting of PWM data (5bits) in current power-down, setting of current power-down timer untilswitched to this PWM data, setting of XSHINT (N-line trigger) numberuntil the current is powered-down, and setting of the number of bits ofPWM.

[0093] Here, regarding the PWM data in the current power-down, althoughthe exciting current is switched from a normal condition to a lowercondition within the same phase in order to prevent noise generated whenthe motor is driven at a low speed, such PWM data corresponds to a lowercurrent value. Further, the current power-down timer is a timer useduntil the exciting current is switched from normal exciting current tolower exciting current within the same phase after the exciting currentis supplied. Further, the XSHINT (N-line trigger) number until thecurrent is powered-down serves to prevent that the time duration formaintaining the higher exciting current due to false running of the CPU1 is not continued so long. Further, the number of bits of the PWM isdata representing how bits among the PWM data having 5-bit width areeffective as the PWM data. When the color image or the image having highresolving power is read with highly fineness at a high speed (this isinstructed from the operating portion (not shown)), great bit number(for example, 5 bits) is set. As a result, since a current wave formhaving correct sine wave can be realized, smooth motor driving ispermitted. If it is not required that the image is read with highlyfineness at the high speed, small bit number (for example, 4 bits) isset. In this case, less smooth motor driving is obtained in comparisonwith the great bit number.

[0094] Again, with reference to the flowchart of FIG. 7, it is judgedwhether the phase data shift signal DATSIF is High or not (step S4002).If DATSIF=H, the PWM counter in the PWM output portion 8 is cleared(step S4003).

[0095] In the step S4002, if the phase data shift signal DATSIF=L, it isjudged whether the PWMSEL signal for switching to the PWM data in thecurrent power-down is 1 or not, i.e., whether the power-down should beeffected or not (step S4004). If PWMSEL=1 (to be powered-down), the PWMdata in the current power-down (stored in the register 11) is selectedby the PWM selector 7 (step S4005). In the step S4004, if PWMSEL=0,then, the PWM counter (setting of the number of bits of PWM) of the PWMoutput portion 8 is counted-up (step S4006). Then, it is judged whetherthe count value reaches the PWM setting value (PWM data value) (stepS4007). If the count value reaches the PWM setting value, the PWM outputvalue is set to 1 (step S4008); whereas, if smaller than the PWM settingvalue, the PWM output value is set to 0 (step S4009). When the PWMcounter counts up to the number of bits of the PWM (counts up to 32 incase of 5 bits), all PWM output values are determined. While PWM outputvalue=1 is being outputted, an ON signal is transmitted to a powersupply (not shown) in the rear stage; whereas, while PWM output value=0is being outputted, an OFF signal is transmitted to the power supply(not shown) in the rear stage. The power supply (not shown) in the rearstage serves to output exciting current having a desired current valuein dependence upon a length of ON/OFF signal. When all PWM output valuesare determined in the step S4008 or S4009, the sequence is returned tothe step S4002, and the similar operations are repeated.

[0096]FIG. 8 is a view showing an example of register setting of theacceleration/deceleration data table comprised of the timer data and thestep data in the stepping motor controlling apparatus shown in FIG. 1.

[0097] In the example shown in FIG. 8, a case where the timer settingregister can be set up to 14 bits×40 and the number of steps settingregister can be set up to 8 bits×40. The acceleration/deceleration datatable number register requires 6 bits since the data table number is 40.In accordance with the set acceleration/deceleration data table number,for example up/down the number of steps of the acceleration/decelerationdata table set within 7 tables (for example, the number of steps=2),table 1 (TIMER1, STEP1) is shifted to table 3 (TIMER3, STEP3) and thento table 5 (TIMER5, STEP5).

[0098] As mentioned above, according to the present invention (e.g.Claims 1 and 16), the burden of the software processing of the CPU canbe reduced, and the motor control corresponding to one-line interruptionin the conventional high speed reading can be realized. Further, evenwhen the motor control is changed during the reading, since the motordriving amount and the reading position of the image are synchronized,the reading can be re-started so that the image can be read withoutdistortion.

[0099] Further, according to the present invention (e.g. Claims 2, 6,17, 21), the burden of the software processing of the CPU can bereduced, and the motor control corresponding to one-line interruption inthe conventional high speed reading can be realized.

[0100] Further, according to the present invention (e.g. Claims 3, 7,18, 22), the acceleration/deceleration of the motor can be realizedwithin the synchronous signal having N-times period while synchronizingwith the line trigger, and the burden of the software processing of theCPU can be reduced and the motor control capable of effectingacceleration/deceleration and corresponding to one-line interruption inthe conventional high speed reading can be realized.

[0101] According to the present invention (e.g. Claims 4, 19), bypreparing the plural motor control modes having different burdens to theCPU, the optimum motor control can be selected.

[0102] According to the present invention (e.g. Claims 5, 20), also inthe synchronous mode, the burden of the software processing of the CPUcan be reduced and the motor control corresponding to one-lineinterruption in the conventional high speed reading can be realized.Further, even when the motor control is changed during the reading,since the motor driving amount and the reading position of the image aresynchronized, the reading can be re-started so that the image can beread without distortion.

[0103] According to the present invention (e.g. Claims 8, 23), theoptimum motor control can be selected in accordance with the image dataamount. Regarding the image having great image data amount, the motorcontrol can be changed during the reading so that the control regardingthe stop of reading in the lack of memory capacity and reading re-startcan be achieved. Regarding the image having small image data amount, themotor control capable of greatly reducing the burden of the softwareprocessing of the CPU can be selected.

[0104] According to the present invention (e.g. Claims 9, 24), theoptimum motor control can be selected in dependence upon whether theimage is color or monochromatic. Regarding the color image, the motorcontrol can be changed during the reading so that the control regardingthe stop of reading in the lack of memory capacity and reading re-startcan be achieved. Regarding an image including a smaller monochromaticimage, the motor control capable of greatly reducing the burden of thesoftware processing of the CPU can be selected.

[0105] According to the present invention (e.g. Claim 10), the burden ofthe software processing of the CPU can be reduced, and the motor controlcorresponding to one-line interruption in the conventional high speedreading can be realized. Further, during the reading, even if the motoris stopped due to lack of the memory capacity, since the motor drivingamount and the reading position of the image are synchronized, thereading can be re-started so that the image can be read withoutdistortion. Further, during the reading, even if the motor is stoppeddue to lack of the memory capacity, since the reading without distortioncan be re-started, the reading can be realized with highly fineness at ahigh speed while reducing the memory capacity.

[0106] According to the present invention (e.g. Claim 11), even if themotor is stopped due to lack of the memory capacity, since the motordriving amount and the reading position of the image are synchronized,the reading can be re-started so that the image can be read withoutdistortion.

[0107] According to the present invention (e.g. Claim 12), even when thereading is re-started, the reading re-start control for realizing themotor control which reduces the burden of the CPU and corresponds toone-line interruption in the conventional high speed reading can beachieved without distortion of the image.

[0108] According to the present invention (e.g. Claim 13), by preparingthe plural motor control modes having different burdens to the CPU, theoptimum motor control can be selected.

[0109] According to the present invention (e.g. Claim 14), the optimummotor control can be selected in accordance with the image data amount.Regarding the image having great image data amount, the motor controlcan be changed during the reading so that the burden of the CPU isreduced and the control regarding the stop of reading in the lack ofmemory capacity and reading re-start can be achieved. Also regarding theimage having small image data amount, the motor control capable ofgreatly reducing the burden of the software processing of the CPU can beselected.

[0110] According to the present invention (e.g. Claim 15), the optimummotor control can be selected in dependence upon whether the image iscolor or monochromatic. Regarding the color image, the motor control canbe changed during the reading so that the control regarding the stop ofreading in the lack of memory capacity and reading re-start can beachieved. Regarding an image including a smaller monochromatic image,the motor control capable of greatly reducing the burden of the softwareprocessing of the CPU can be selected.

[0111] According to the present invention (e.g. Claims 25, 26), theoptimum exciting current suitable for the image can be obtained, therebypermitting the stable motor driving.

[0112] Further, according to the present invention (e.g. Claim 27),since the step-up or the step-down of the acceleration/deceleration datatable is effected on the basis of the step-up number or the step-downnumber held in the step-up or step-down number storing means 23, there-writing of the registers under no load can be achieved, and theacceleration/deceleration control exceeding theacceleration/deceleration table number can be realized by combiningup/down of the acceleration/deceleration data table register, therebyachieving reduction of the burden of the software processing and thestable operation with respect to such control. Further, when the motorcontrol unit is constituted by ASIC and the like, reduction of theburden of the software processing and reduction of gate scale can becompatible, thereby subdividing the acceleration range.

[0113] Further, according to the present invention (e.g. Claim 28), inthe stepping motor controlling apparatus, since the motor control unit 3has the fourth storing means 19 for holding the table number of theacceleration/deceleration tables and the step-up or the step-down of theacceleration/deceleration table is stopped on the basis of the tablenumber held by the fourth storing means 19, the data number of theacceleration/deceleration data to be written in the program area can bereduced.

What is claimed is:
 1. An apparatus for controlling a stepping motor,comprising: synchronous signal generating means for generating asynchronous signal having a period corresponding to N (natural number)times of one-line of an image; line trigger producing means forproducing N (in number) line triggers in synchronous with generation ofthe synchronous signal; a motor control unit for controlling saidstepping motor; and a CPU for controlling said motor control unit insynchronous with the generation of the synchronous signal, wherein saidmotor control unit effects motor control until at least next synchronoussignal is reached on the basis of the line triggers.
 2. A stepping motorcontrolling apparatus according to claim 1, wherein said motor controlunit includes first memory means for holding timer data for advancing aphase of said stepping motor and second memory means for holding thenumber of steps of the timer data, and said stepping motor is controlledon the basis of the timer data and the number of steps.
 3. A steppingmotor controlling apparatus according to claim 2, wherein said motorcontrol unit is synchronized with the line triggers produced by saidproducing means and controls acceleration/deceleration of said steppingmotor by switching acceleration/deceleration data tables comprised ofthe timer data and the number of steps.
 4. An apparatus for controllinga stepping motor, comprising: synchronous signal generating means forgenerating a synchronous signal for synchronizing with a motor controlunit; a motor control unit for controlling said stepping motor; and aCPU for controlling said motor control unit; and line trigger producingmeans for producing N (in number) line triggers, wherein said motorcontrol unit has a synchronous mode for controlling said stepping motorin synchronous with generation of the synchronous signal and anon-synchronous mode for controlling said stepping motor regardless ofthe generation of the synchronous signal, when the synchronous mode isselected, the motor control synchronous with the synchronous signal iseffected, and when the non-synchronous mode is set, said line triggerproducing means generates line triggers which are not synchronous withthe synchronous signal and said motor control unit controls said motoron the basis of the line triggers which are not synchronous with thesynchronous signal.
 5. A stepping motor controlling apparatus accordingto claim 4, wherein said synchronous signal generating means generatesthe synchronous signal having a period corresponding to N (naturalnumber) times of one-line of an image, and, when the synchronous mode isselected, said line trigger producing means produces the line triggersynchronous with the synchronous signal and said motor control uniteffects motor control until at least next synchronous signal is reachedon the basis of the line trigger synchronous with the synchronoussignal.
 6. A stepping motor controlling apparatus according to claim 4,wherein said motor control unit includes first memory means for holdingtimer data for advancing a phase of said stepping motor and secondmemory means for holding the number of steps of the timer data, and saidstepping motor is controlled on the basis of the timer data and thenumber of steps.
 7. A stepping motor controlling apparatus according toclaim 6, wherein said motor control unit is synchronized with the linetriggers produced by said producing means and controlsacceleration/deceleration of said stepping motor by switchingacceleration/deceleration data tables comprised of the timer data andthe number of steps.
 8. A stepping motor controlling apparatus accordingto claim 4 or 5, wherein the synchronous mode is selected in case of animage having great memory usage amount and the non-synchronous mode isselected in case of an image having small memory usage amount.
 9. Astepping motor controlling apparatus according to claim 4 or 5, whereinthe synchronous mode is selected in case of a color image and thenon-synchronous mode is selected in case of a monochromatic image. 10.An apparatus for reading an image, comprising: reading means for readingan image with line unit; storing means for storing the read image;synchronous signal generating means for generating a synchronous signalhaving a period corresponding to N (natural number) times of one-line ofthe image; line trigger producing means for producing N (in number) linetriggers in synchronous with generation of the synchronous signal; amotor control unit for effecting acceleration/deceleration control ofsaid stepping motor on the basis of the line triggers; a CPU forcontrolling said motor control unit in synchronous with the generationof the synchronous signal; judging means for judging a usage state ofsaid storing means; and stop control means for causing said CPU toeffect control for stopping said motor with respect to said motorcontrol unit in synchronous with the generation of the synchronoussignal when said judge means judges that vacant capacity of said storingmeans is smaller than a predetermined value or that usage amount of saidstoring means is smaller than a predetermined value, wherein said motorcontrol unit effects stop control for decelerating and stopping saidmotor on the basis of the line triggers by means of said stop controlmeans.
 11. An image reading apparatus according to claim 10, whereinsaid judging means includes reading restart instructing means forinstructing re-start of reading when it is judged that the vacantcapacity of said storing means is greater than the predetermined value.12. An image reading apparatus according to claim 10, wherein, when saidreading re-start instructing means instructs the re-start of reading insynchronous with the generation of the synchronous signal, said motorcontrol unit accelerates said motor to reversely rotate said motor up toa position sufficient to effect fixed speed driving to a decelerationstarting position from which deceleration is started by the stopinstruction, thereby permitting the re-start of reading at a high speedagain.
 13. An image reading apparatus according to claim 10, whereinsaid motor control portion has a synchronous mode for controlling saidstepping motor in synchronous with the generation of the synchronoussignal and a non-synchronous mode for controlling said stepping motorregardless of the generation of the synchronous signal, and when thenon-synchronous mode is selected, said line trigger producing meansgenerates the N (in number) line triggers regardless of the generationof the synchronous signal and said motor control unit controls saidmotor on the basis of the N line triggers which are not synchronous withthe synchronous signal.
 14. An image reading apparatus according toclaim 13, wherein the synchronous mode is selected in case of an imagehaving great memory usage amount and the non-synchronous mode isselected in case of an image having small memory usage amount.
 15. Animage reading apparatus according to claim 13, wherein the synchronousmode is selected in case of a color image and the non-synchronous modeis selected in case of a monochromatic image.
 16. An apparatus forcontrolling a stepping motor, comprising: synchronous signal generatingmeans for generating a synchronous signal having a period correspondingto N (natural number) times of one-line of an image; line triggerproducing means for producing N (in number) line triggers in synchronouswith generation of the synchronous signal; a motor control unit forcontrolling said stepping motor; and instruction receiving means forreceiving a motor control instruction from a CPU in synchronous with thegeneration of the synchronous signal, wherein said motor control uniteffects motor control until at least next synchronous signal is reachedon the basis of the line triggers.
 17. A stepping motor controllingapparatus according to claim 16, wherein said motor control unitincludes first memory means for holding timer data for advancing a phaseof said stepping motor and second memory means for holding the number ofsteps of the timer data, and said stepping motor is controlled on thebasis of the timer data and the number of steps.
 18. A stepping motorcontrolling apparatus according to claim 17, wherein said motor controlunit is synchronized with the line triggers produced by said producingmeans and controls acceleration/deceleration of said stepping motor byswitching acceleration/deceleration data tables comprised of the timerdata and the number of steps.
 19. An apparatus for controlling astepping motor, comprising: synchronous signal receiving means forreceiving a synchronous signal for synchronizing with a motor controlunit; a motor control unit for controlling said stepping motor;instruction receiving means for receiving motor control instruction froma CPU; and line trigger producing means for producing line triggers at aperiod corresponding to one line of an image, wherein said motor controlunit has a synchronous mode for controlling said stepping motor insynchronous with receipt of the synchronous signal and a non-synchronousmode for controlling said stepping motor regardless of receipt of thesynchronous signal, when the synchronous mode is selected, saidinstruction receiving means receives the motor control instruction fromsaid CPU in synchronous with generation of the synchronous signal andsaid motor control unit effects motor control on the basis of theinstruction received by said instruction receiving means, and when thenon-synchronous mode is set, said line trigger producing means producesline triggers which are not synchronous with the synchronous signal andsaid motor control unit effects the motor control on the basis of theline triggers which are not synchronous with the synchronous signal. 20.A stepping motor controlling apparatus according to claim 19, whereinsaid synchronous signal receiving means receives the synchronous signalhaving a period corresponding to N (natural number) times of one-line ofthe image, and wherein, when the synchronous mode is selected, said linetrigger producing means produces a line trigger which is synchronouswith the synchronous signal and said motor control unit effects themotor control until at least next synchronous signal is reached on thebasis of the line trigger which is synchronous with the synchronoussignal.
 21. A stepping motor controlling apparatus according to claim19, wherein said motor control unit includes first memory means forholding timer data for advancing a phase of said stepping motor andsecond memory means for holding the number of steps of the timer data,and said stepping motor is controlled on the basis of the timer data andthe number of steps.
 22. A stepping motor controlling apparatusaccording to claim 21, wherein said motor control unit is synchronizedwith the line triggers produced by said producing means and controlsacceleration/deceleration of said stepping motor by switchingacceleration/deceleration data tables comprised of the timer data andthe number of steps.
 23. A stepping motor controlling apparatusaccording to claim 19, wherein the synchronous mode is selected in caseof an image having great memory usage amount and the non-synchronousmode is selected in case of an image having small memory usage amount.24. A stepping motor controlling apparatus according to claim 19,wherein the synchronous mode is selected in case of a color image andthe non-synchronous mode is selected in case of a monochromatic image.25. A stepping motor controlling apparatus according to claim 1, 4, 16or 19, wherein said motor control unit includes PWM output data storingmeans for holding PWM output data having a predetermined the number ofbits for determining an exciting current for said stepping motor, andPWM output means for outputting the PWM data stored in said PWM outputdata storing means in synchronous with a phase of said stepping motor,and wherein said stepping motor is controlled by setting the number ofbits of the PWM data outputted from said PWM output means.
 26. An imagereading apparatus according to claim 10, wherein said motor control unitincludes PWM output data storing means for holding PWM output datahaving a predetermined the number of bits for determining excitingcurrent for said stepping motor, and PWM output means for outputting thePWM data stored in said PWM output data storing means in synchronouswith a phase of said stepping motor, and wherein said stepping motor iscontrolled by setting the number of bits of the PWM data outputted fromsaid PWM output means.
 27. A stepping motor controlling apparatusaccording to claim 3, 7, 18 or 22, wherein said motor control unitincludes step-up or step-down number storing means for holding a step-upnumber or a step-down number of said acceleration/deceleration table,and step-up or step-down of said acceleration/deceleration table iseffected on the basis of the step-up number or the step-down number heldby said step-up or step-down number storing means.
 28. A stepping motorcontrolling apparatus according to claim 26, wherein said motor controlunit includes table number storing means for holding a table number ofacceleration/deceleration tables, and step-up or step-down of saidacceleration/deceleration table is stopped on the basis of the tablenumber held by said table number storing means.
 29. A method forcontrolling a stepping motor, comprising the steps of: generating asynchronous signal having a period corresponding to N (natural number)times of one-line of an image; producing N (in number) line triggers insynchronous with generation of the synchronous signal; controlling saidstepping motor by means of a motor control unit; and controlling saidmotor control unit in synchronous with the generation of the synchronoussignal by a CPU, wherein said motor control unit effects motor controlunit at least next synchronous signal is reached on the basis of theline triggers.
 30. A stepping motor controlling method according toclaim 29, wherein said motor control unit includes first memory meansfor holding timer data for advancing a phase of said stepping motor andsecond memory means for holding the number of steps of the timer data,and said stepping motor is controlled on the basis of the timer data andthe number of steps.
 31. A stepping motor controlling method accordingto claim 30, wherein said motor control unit is synchronized with theline triggers and controls acceleration/deceleration of said steppingmotor by switching acceleration/deceleration data tables comprised ofthe timer data and the number of steps.
 32. A method for controlling astepping motor, comprising the steps of: generating a synchronous signalfor synchronizing with a motor control unit by synchronous signalgenerating means; controlling said stepping motor by means of said motorcontrol unit; and controlling said motor control unit by a CPU; andproducing N (in number) line triggers by line trigger producing means,wherein said motor control unit has a synchronous mode for controllingsaid stepping motor in synchronous with generation of the synchronoussignal and a non-synchronous mode for controlling said stepping motorregardless of the generation of the synchronous signal, when thesynchronous mode is selected, the motor control synchronous with thesynchronous signal is effected, and when the non-synchronous mode isset, said line trigger producing means generates line triggers which arenot synchronous with the synchronous signal and said motor control unitcontrols said motor on the basis of the line triggers which are notsynchronous with the synchronous signal.
 33. A stepping motorcontrolling method according to claim 32, wherein said synchronoussignal generating means generates the synchronous signal having a periodcorresponding to N (natural number) times of one-line of an image, and,when the synchronous mode is selected, said line trigger producing meansproduces the line trigger synchronous with the synchronous signal andsaid motor control unit effects motor control until at least nextsynchronous signal is reached on the basis of the line triggersynchronous with the synchronous signal.
 34. A stepping motorcontrolling method according to claim 32, wherein said motor controlunit includes first memory means for holding timer data for advancing aphase of said stepping motor and second memory means for holding thenumber of steps of the timer data, and said stepping motor is controlledon the basis of the timer data and the number of steps.
 35. A steppingmotor controlling method according to claim 34, wherein said motorcontrol unit is synchronized with the line triggers produced by saidproducing means and controls acceleration/deceleration of said steppingmotor by switching acceleration/deceleration data tables comprised ofthe timer data and the number of steps.
 36. A stepping motor controllingmethod according to claim 32 or 33, wherein the synchronous mode isselected in case of an image having great memory usage amount and thenon-synchronous mode is selected in case of an image having small memoryusage amount.
 37. A stepping motor controlling method according to claim32 or 33, wherein the synchronous mode is selected in case of a colorimage and the non-synchronous mode is selected in case of amonochromatic image.
 38. A method for reading an image, comprising thesteps of: reading an image with line unit; storing the read image bystoring means; generating a synchronous signal having a periodcorresponding to N (natural number) times of one-line of the image;producing N (in number) line triggers in synchronous with generation ofthe synchronous signal by line trigger producing means; effectingacceleration/deceleration control of said stepping motor on the basis ofthe line triggers by means of a motor control unit; controlling saidmotor control unit in synchronous with the generation of the synchronoussignal; judging a usage state of said storing means by means of judgingmeans; and causing said CPU to effect control for stopping said motorwith respect to said motor control unit in synchronous with thegeneration of the synchronous signal when it is judged that vacantcapacity of said storing means is smaller than a predetermined value orthat usage amount of said storing means is smaller than a predeterminedvalue, by means of stop control means, wherein said motor control uniteffects stop control for decelerating and stopping said motor on thebasis of the line triggers by means of said stop control means.
 39. Animage reading method according to claim 38, wherein said judging meansincludes reading re-start instructing means for instructing re-start ofreading when it is judged that the vacant capacity of said storing meansis greater than the predetermined value.
 40. An image reading methodaccording to claim 38, wherein, when said reading re-start instructingmeans instructs the re-start of reading in synchronous with thegeneration of the synchronous signal, said motor control unitaccelerates said motor to reversely rotate said motor up to a positionsufficient to effect fixed speed driving to a deceleration startingposition from which deceleration is started by the stop instruction,thereby permitting the re-start of reading at a high speed again.
 41. Animage reading method according to claim 38, wherein said motor controlunit has a synchronous mode for controlling said stepping motor insynchronous with the generation of the synchronous signal and anon-synchronous mode for controlling said stepping motor regardless ofthe generation of the synchronous signal, and when the non-synchronousmode is selected, said line trigger producing means generates the N (innumber) line triggers regardless of the generation of the synchronoussignal and said motor control unit controls said motor on the basis ofthe N line triggers which are not synchronous with the synchronoussignal.
 42. An image reading method according to claim 41, wherein thesynchronous mode is selected in case of an image having great memoryusage amount and the non-synchronous mode is selected in case of animage having small memory usage amount.
 43. An image reading methodaccording to claim 41, wherein the synchronous mode is selected in caseof a color image and the non-synchronous mode is selected in case of amonochromatic image.
 44. A method for controlling a stepping motor,comprising the steps of: generating a synchronous signal having a periodcorresponding to N (natural number) times of one-line of an image;producing N (in number) line triggers in synchronous with generation ofthe synchronous signal; controlling said stepping motor by means of amotor control unit; and receiving a motor control instruction from a CPUin synchronous with the generation of the synchronous signal byinstructing receiving means, wherein said motor control unit effectsmotor control until at least next synchronous signal is reached on thebasis of the line triggers.
 45. A stepping motor controlling methodaccording to claim 44, wherein said motor control unit includes firstmemory means for holding timer data for advancing a phase of saidstepping motor and second memory means for holding the number of stepsof the timer data, and said stepping motor is controlled on the basis ofthe timer data and the number of steps.
 46. A stepping motor controllingmethod according to claim 45, wherein said motor control unit issynchronized with the line triggers produced by said producing means andcontrols acceleration/deceleration of said stepping motor by switchingacceleration/deceleration data tables comprised of the timer data andthe number of steps.
 47. A methods for controlling a stepping motor,comprising the steps of: receiving a synchronous signal forsynchronizing with a motor control unit; controlling said stepping motorby means of said motor control unit; receiving motor control instructionfrom a CPU by means of instruction receiving means; and producing linetriggers at a period corresponding to one line of an image by means ofline trigger producing means, wherein said motor control unit has asynchronous mode for controlling said stepping motor in synchronous withreceipt of the synchronous signal and a non-synchronous mode forcontrolling said stepping motor regardless of receipt of the synchronoussignal, when the synchronous mode is selected, said instructionreceiving means receives the motor control instruction from said CPU insynchronous with generation of the synchronous signal and said motorcontrol unit effects motor control on the basis of the instructionreceived by said instruction receiving means, and when thenon-synchronous mode is set, said line trigger producing means producesline triggers which are not synchronous with the synchronous signal andsaid motor control unit effects the motor control on the basis of theline triggers which are not synchronous with the synchronous signal. 48.A stepping motor controlling method according to claim 47, wherein saidsynchronous signal receiving means receives the synchronous signalhaving a period corresponding to N (natural number) times of one-line ofthe image, and wherein, when the synchronous mode is selected, said linetrigger producing means produces a line trigger which is synchronouswith the synchronous signal and said motor control unit effects themotor control until at least next synchronous signal is reached on thebasis of the line trigger which is synchronous with the synchronoussignal.
 49. A stepping motor controlling method according to claim 47,wherein said motor control unit includes first memory means for holdingtimer data for advancing a phase of said stepping motor and secondmemory means for holding the number of steps of the timer data, and saidstepping motor is controlled on the basis of the timer data and thenumber of steps.
 50. A stepping motor controlling method according toclaim 49, wherein said motor control unit is synchronized with the linetriggers produced by said producing means and controlsacceleration/deceleration of said stepping motor by switchingacceleration/deceleration data tables comprised of the timer data andthe number of steps.
 51. A stepping motor controlling method accordingto claim 47, wherein the synchronous mode is selected in case of animage having great memory usage amount and the non-synchronous mode isselected in case of an image having small memory usage amount.
 52. Astepping motor controlling method according to claim 47, wherein thesynchronous mode is selected in case of a color image and thenon-synchronous mode is selected in case of a monochromatic image.
 53. Astepping motor controlling method according to claim 29, 32, 44 or 47,wherein said motor control unit includes PWM output data storing meansfor holding PWM output data having a predetermined the number of bitsfor determining an exciting current for said stepping motor, and PWMoutput means for outputting the PWM data stored in said PWM output datastoring means in synchronous with a phase of said stepping motor, andwherein said stepping motor is controlled by setting the number of bitsof the PWM data outputted from said PWM output means.
 54. An imagereading method according to claim 38, wherein said motor control unitincludes PWM output data storing means for holding PWM output datahaving a predetermined the number of bits for determining excitingcurrent for said stepping motor, and PWM output means for outputting thePWM data stored in said PWM output data storing means in synchronouswith a phase of said stepping motor, and wherein said stepping motor iscontrolled by setting the number of bits of the PWM data outputted fromsaid PWM output means.
 55. A stepping motor controlling method accordingto claim 31, 35, 46 or 50, wherein said motor control unit includesstep-up or step-down number storing means for holding a step-up numberor a step-down number of said acceleration/deceleration table, andstep-up or step-down of said acceleration/deceleration table is effectedon the basis of the step-up number or the step-down number held by saidstep-up or step-down number storing means.
 56. A stepping motorcontrolling method according to claim 54, wherein said motor controlunit includes table number storing means for holding a table number ofacceleration/deceleration tables, and step-up or step-down of saidacceleration/deceleration table is stopped on the basis of the tablenumber held by said table number storing means.